A study carried out in France, the USA and Japan on 2760 persons aged between 20 and 45 has indicated that 60% of the population suffers from eye fatigue. The eyes of persons affected by eye fatigue can no longer be set to an optimal sharpness and the ability of these persons to focus reduces. This leads to blurry vision and strain discomfort. This strain discomfort in particular occurs in the case of stress, artificial light, long periods of work in front of a computer, et cetera. The cause of this discomfort is an ever increasing load in the near range which occurs over a relatively long period of time.
Various spectacles lens manufacturers have identified this problem and offer specially designed spectacles lenses for non-presbyopic persons. Under the “Anti-Fatigue” brand, Essilor offers spectacles lenses, the near portion of which has an increased power of +0.60 D compared to an afocal lens or a conventional single vision lens. This increased near portion power has an accommodation-supporting power so as to reduce accommodation stress in the case of visual tasks in the near range. Such a spectacles lens is also described in U.S. Pat. No. 7,540,610 B2. It is also known to provide a convergence support in the form of an increased prismatic power in the near portion in order to reduce the convergence stress in the case of visual tasks in the near range. Combinations of both supporting measures are also possible.
Even though, in principle, the aforementioned visual stress-reducing spectacles lenses have proven their worth, a large proportion of non-presbyopic persons who wear spectacles with the above-described visual stress-reducing spectacles lenses were found nevertheless to complain about eye fatigue.